Chapter 8 review (AP stats)

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Transcript of Chapter 8 review (AP stats)

Chapter 8

8:1 Estimating with confidence 8:2 Estimating a Population proportion Standard Error: is

when the standard deviation of a statistic is estimated from data (page 487)8:3 Estimating a Population Mean One Sample Z Interval for a Populations Mean page 499Confidence Interval (page 472)for a parameter has 2 parts:1.) An interval calculated from the data, which has the form: estimate + or - margin of errorMargin of Error: tells how close the estimate tends to be to the unknown parameter in repeated random sampling 2.) Confidence level: which gives the overall success rate of the method for calculating the confidence interval. That is, in the C% of all possibles samples, the method would yield an interval that captures the true parameter value. Confidence Intervals: the Basics Point Estimator: is a statistic that provides an estimate of a population parameter. (page 469)One Sample T interval for a Population Meanpage 507 Interpreting Confidence levels and Confidence Intervals (page 474)Confidence Level: to say that we have a95% confidence is shorthand for "95% of all possible samples of a given size from this population will result in an interval that captures the unknown parameter.Confidence Interval: to interpret a C% confidenceinterval for an unknown parameter, say " we are C% confident that the interval from ___ to ___ captures the actual value of the [population parameter in context]Exercise #3 page 481Calculating a confidence interval The confidence interval for estimating a population parameter has the form statistic + or - (critical value) *(Standard Deviation of statistic)where the statistic we used is the piont estimator for the parameter.Conditions for constructing a Confidence Interval Random: the data come from a well-designed random samples or randomized experiment Normal: that sampling distribution of the statistic is approximately Normal Independent: individual observations are independent. when sampling without replacement, the sample sizeOne Sample Z Interval for a Population Proportion(page 489)Margin of error (page 493)Used when Standard Deviations and mean are known

Used when Standard Deviation is Unknown Random: SRS or Randomized experiment Normal: Population has a normal distribution or sample size is large (n > or = to 30) Independent: check with the 10% condition: verify that the sample size is no more than 1/10 of the population size